Scanner scanner=new Scanner(System.in);
System.out.print("请输入要输出的行数：");
int a=scanner.nextInt();
int i,j;
for(i=1;i<=a;i++){
	for(j=1;j<=i-1;j++){
		System.out.print(" ");
	}
	for(j=1;j<=2*a+1-2*i;j++){
		System.out.print("*");
	}
	System.out.println();
}
